§ 50. Melody. — As movement is both temporal and spatial, so melody is both temporal and qualitative. It presupposes both clang and rhythm.
A melody is, in the first place, a succession of single clangs. These clangs cannot be chosen at random; we know that a mere sounding of clangs, one after the other, does not give rise to what we call a tune. The composer has always to select from a definite series of clangs. Or, in other words, every melody, however primitive it may be, is composed in a certain scalcy however rudimentary. Its clangs, i.e., are chosen from a restricted number, arranged at approximately fixed intervals.
It is probable that all scales begin with the interval of the descending fourth. A c being given, the first note to be fixed is the G of the octave below. After this G — or possibly, in some few instances, before it, as the first added note — comes the ascending fifth, the g of the octave of which c is the lowest note. The other notes of the scale are gradually established between these limits, G-g, as the musical appreciation of mankind develops.
We are accustomed to think of a scale as beginning in the bass and continuing upwards towards the treble. It is natural, how- ever, that the primitive scales should descend, run from treble to bass. The earliest melody must have been very like our recita- tive: and the voice falls or drops at the end of each sentence.
The descending scale rests, first of all, upon the fourth below its starting-point, because this interval is the ordinary drop of the voice in speaking. It rises, first of all, to the fifth above its start- ing-point, because this is the ordinary rise of the voice in ques- tioning.
The scale which has been universally adopted in Western music is an ascending scale of twelve notes (semitones) to the octave. These notes are c, %c, d, id, e, /, tf, g, tg, a, ia, b. Traces of other scales are occasionally found: e.g., in Scotch bagpipe music.
As the scale becomes complex, the rules of melody necessarily 1 82 Perception and Idea become precise. Hence we have such canons as that the melody must begin and end with the same note, the ' tonic ' clang. We pass from first to last note, from tonic to tonic clang, through clangs whose overtones are partially identical; so that a conti- nuity of movement is secured, similar to that which we have explained by the persistence of sensation, as after-image or memory, in tactual and visual movement (§ 46).
The semitone is not by any means the least difference of pitch that the ear can discriminate (§ 13). But it is the least difference which the voice can sing with any accuracy; and we have seen that the larynx is the earliest musical instrument. The singing of two successive semitones, then, means a just noticeable adjustment of the laryngeal muscles, a just noticeable difference of two com- plexes of strain sensations. The musical scale was formed not by ear, but by voice; and this is one of the reasons why music uses so few of the tones.
Weber's law tells us that equal differences of sensation cor- respond to relatively equal differences of stimulus. Whether the vocal cords are slack or tense, therefore, their tension must be in- creased in the same proportion, if we are to get a just noticeable difference of strain sensation, i.e., the difference of a semitone in the vibration rates of the cords. Hence we should expect to find what is actually the case: that as the tc has T)^ vibrations in the first second when the c has 32, it has 72 when the c has 64, 144 when the c has 128, and so on.
A melody is, in the second place, a succession of rhythms. It consists of a number of measures, rounded to phrases and periods. The rhythm helps to hold the changing clangs together, as the melody proceeds; and the return of melody to its tonic clang helps to hold together the series of rhythms.
We have in a given melody, then, a qualitative whole in a temporal setting. The melodic idea is more complex than those which we have discussed hitherto. It lies on the border-line between an idea and a successive association of ideas.
§ 51- The Fimction of the Idea 183 § 51. The Function of the Idea. — Two of the questions of § 43 have now been answered: we have seen how ideas are formed, and which of the four attributes of sensation are of the greatest importance for their production.' We have not yet answered the third question, — under what circumstances the idea acquires its unity or singleness for mental experience.
Not every sensation complex has this unity or single- ness; so that not every sensation complex can be termed a perception or idea. The visual quality of yellow and the tonal quality of the middle c may be together in con- sciousness. Yet there is no yellow-r or ^-yellow idea. On the other hand, not every complex of sensations which can be called unitary or single can also be called a perception or idea. The experiences of drowsiness, fatigue, health, etc. (§21) are complexes of sensations and affection closely connected; yet we should hardly speak of them as perceptions or ideas. Despite their singleness in experience, we term them groups of or- ganic sensations, or, less accurately, organic sensations. The unity or singleness of the idea must, therefore, be of a special kind and result from special conditions.
The idea is unitary because it is the conscious repre- sentative of a single object or process in the outside world. It is a complex of elementary mental processes which, in Its entirety, corresponds to the various aspects or phases of a physical object or process. The object or process appeals to us in different ways, by different sense chan- nels; and each kind of appeal is represented in the idea. The reason for its singleness, its self-consistency, is, therefore, a biological reason: what the organism finds together in the world in which it lives, remains together 184 Perception and Idea in perception or idea. The physical processes underlying the visual quality yellow and the auditory quality c are not connected together, and consequently the qualities them- selves cannot join to form an idea. On the other hand, the qualities corresponding to the organic, bodily processes underlying health, etc., are never found apart, and their analysis is very difficult. Hence they are ordinarily re- garded as sensations. When analysed, however, the com- plexes prove to correspond to different physical processes at different parts of the body. Hence to the psychologist they form a group of sensations, not an idea. Different from both the yellow-<; complex and these complexes of organic sensations is the simple clang, or note. Here the qualities are so closely blended that the whole is popularly regarded as a sensation. When analysed, it falls into a number of constituents; but these all correspond to the various phases of one physical movement-process, — and the clang is accordingly a true perception or idea.
We are now in a position to understand why there should be those conflicts, between ideas derived from different senses, of which we have more than once spoken (§§ 44 ff.). Although all the sense-organs are in the service of the same organism, each of them mirrors or reflects the objects and processes of the physi- cal world in its own special way. As the senses stand upon dif- ferent levels, some being more and some less highly developed, discrepancies must necessarily arise when two of them furnish the same kind of idea. The appeal is always to vision, — to the most highly developed class of four-attribute sensations. "Seeing is beheving."
The ideas which conflict with visual ideas, and which for that reason we refuse to accept, are termed illusory ideas. They are deceptive ideas, ideas which ' play with ' us. If two blunt points are set down upon the skin of the back at a distance of 60 mm.
§51- The Fujictio7i of the Idea apart, they are taken to be but one impression, i.e., tactually localised at the same place. This tactual idea of locality is illusory; we have only to see the stimuli to believe that they are two. — Draw a pair of compasses, whose points are 2 cm. apart, across the face from ear to ear, so that one point travels over the upper lip, and the other between lower hp and chin. Your tact- ual idea of the figure described will be that of an oval. The points seem to come together at the ears, where you cannot localise impressions accurately, and to separate at the lips, where your power of localisation is greater. This idea of an oval is illusory: sight would tell you that the compass points are describ- ing two parallel hues. — The size of the cavity of a hollow tooth, as perceived by the tip of the tongue, is illusory, as are also the differences which the skin perceives in the rate of a movement known by the eye to be uniform. — If as we he upon the tilt- board the strains and pressures in head and neck and back tell us that we are standing upon our head, and we then open the eyes and ' see ' that we are only 60° from the horizontal, we reject the tactual idea and accept the visual. The former is illusory.
Yet we are often deceived by the eye itself, and know that we are deceived. In such cases we speak, not of a visual perception or idea, but of an optical illusio7i. Thus the eye declares that the railway lines along which we are looking meet at the horizon, and that a square figure is higher than it is broad. The eye, that is to say, is, no more than the skin, an absolutely reliable mirror of external ob- jects and processes: if we did not know that the hnes are parallel and that the square is equilateral, the eye would de- ceive us.
l^igure 8 gives mstances of optical illusions in the sphere of extensive ideas. The two cross- lines in a seem to be parts of one and the same line. This is not lS6 Perceptioji and Idea the case; so that we have in the figure an illusion of position. In h a square is inscribed in a circle. But the four arcs appear to belong to smaller circles, and the sides of the square to bend inwards; so that the figure seems to be of the same type as c. We have in it an illusion of form. The open semicircle in d looks larger than the closed. Both are of the same size: the figure gives us an illusion of magnitude.
The first of these illusions is the result of two factors. We always overestimate vertical distances, because it requires more effort — the strain sensations must be stronger — to move the eye up than to move it out or in. Hence the left-hand cross-line is put too high in our idea, and its continuation accordingly looked for at too high a point on the right of the rectangle. We also overestimate the size of small angles. Since the acute angle made with the rectangle by the left-hand cross-line is overestimated, the continuation of the line on the right will again be looked for too high up. — The second illusion also depends on the fact of the overestimation of small angles. The angles made by the sides of the square with the four arcs are regarded as larger than they really are. The illusion necessarily follows. The overestimation itself is probably due to the passing of the eye along the lines forming the angle, and the consequent forcing-apart of those lines in perception. — The third illusion is accounted for by the fact that the open semicircle offers no impediment to eye movement, while the closed figure seems to check it above and below.
We have a visual illusion of movement from what is called the stroboscope. A series of instantaneous photographs of some moving object, e.g., a flying bird, are taken in rapid succession. These are pasted at regular intervals on the inside of a cardboard cylinder. In the wall of the cylinder, above the photographs, are cut a number of narrow vertical shts, each one directly opposite to one of the pictures. Twirl the cylinder round, while you look down through the slits at the photographs. You will see, not the separate phases of the flying movement, but a continuous flight. The reason is, that each impression persists for a little time after the stimulus has passed by.
The phenomena of contrast furnish instances of illusions of § 51- TJie F2t7iction of the Idea 187 visual quality. If a light grey square is laid upon a background of deep red, it appears not grey but greenish, etc. The colours and brightnesses must not be too intense, or they are too much themselves to be affected by neighbouring colours and bright- nesses; and they must not be too weak, or there is not enough quahty in them, so to speak, for contrast effects to arise. No satisfactory explanation of contrast has yet been given.
In all these cases, vision is the test of vision; we know from the eye that the eye has deceived us. We soon learn by experi- ence that the appearance of objects in the field of vision alters as the position of the eyes alters; the table that looks square from one point of view seems to be a trapezoid from another. Hence it becomes necessary, for practical purposes, to construct an ideal or standard eye, and to accept its verdict in all cases where the real eyes leave us in doubt, or where two actual visual perceptions contradict each other. The ideal or standard eye is the nieasnr- ing or mathematical eye; the eye that perceives distances and sizes and forms in terms of yards or metres, and directions in terms of angular distance from some fixed point or line. The measuring eye abstracts from all the varying conditions under which an object is seen, and perceives it always under standard conditions. Where we stand the railway lines are 4 ft. 8^ in. apart j if we walk to the point where the horizon lay, they are there too 4 ft. Z\ in. apart: therefore they do not meet at the horizon, as the eye which sees the whole extent at once would have us believe they do. The square looks higher than it is broad; but the height is i cm. and the breadth i cm.: there- fore the figure is equilateral.
CHAPTER VIII The Association of Ideas § 52. The Nature and Forms of Association. — Our dis- cussion of the perception or idea has brought us face to face with concrete facts, with actual items of mental experience.
But although the idea is an item of experience, and may thus be regarded as complete in itself, it is not a * thing,' definite in outline and impermeable to outside influences. Looked at from within, it is a complex of fluid processes. Even the most clear-cut idea, the idea of a 'thing,' gives evidence in support of this statement: its centre of in- terest, the part-process in it which holds the attention, is constantly changing (§ 2). Looked at from without, it is itself a fluid process; a process of varying extent and varying form, set in the midst of a tangle of similar pro- cesses, i.e., of a consciousness.
In § 9 we compared consciousness to a fresco; it is a whole in which there are no breaks, but a smooth connection of part with part. The comparison will be useful to us now, as an aid to our understanding of the nature of the idea. The idea is, in one sense, something by itself, complete in itself; just as the figures in the fresco are, as human figures, complete in themselves and separable from the rest of the painting. But the idea is, in another sense, incomplete; it is never found alone, out of its mental setting; it runs over into other ideas. And the figures in the fresco are also incomplete, gaining their full significance only § 52. NaUire and Forms of Association 189 as parts of the painter's total conception, while their outlines are not sharp and rigid, but merge in their background at the same time that they stand out upon it. The figures imply the whole fresco: the ideas imply the whole of consciousness.
It is natural, then, that the connection of elementary processes should not stop short at the idea. Just as the sensations which are set up at the same time by the exci- tation of different bodily organs, or of different parts of the same organ, unite to form an idea or perception, so do the sensations which have entered into different ideas or perceptions unite to form still more complex processes, still larger sections of mental experience. And just as we passed from the consideration of sensation to that of per- ception or idea, so we must now pass from this to the con- sideration of what is called the * association of ideas.'
Suppose that I am sitting in my study, and find my train of thought suddenly interrupted by the perception of a loud rumbling noise. The perception may be the whole of the experience: I may feel a momentary impatience at the interruption, and then return at once to my work. But, on the other hand, the perception may call up in my mind the vague picture of some heavy vehicle on the street below my window; and if, earlier in the day, I have seen a traction engine somewhere in the neighbourhood, this visual picture may be made definite, and further con- nected with the verbal idea 'traction engine.' There is no appreciable lapse of time between the original sound per- ception and the appearance of these other ideas: the noise is no sooner heard than picture and word are together with it in consciousness. In such cases we speak of a simultaneous association.
This, again, may be the whole of the experience: with 190 The Association of Ideas the completion of the simultaneous association I may return to my work. But the interruption may go still farther. The idea of the traction engine may arouse in my mind the picture of an accident that I witnessed some years ago, — the quick turn of a similar engine round a sharp corner, the sideward spring of a horse, startled by sight and sound, and the overthrow of the carriage. This in turn may give place to the picture of the man who jostled me as the crowd ran towards the scene of the mis- hap. And so the process is continued. ' He was curi- ously like Jones: I have not seen Jones since I was at school: the first time I saw him there he was eating sand- wiches on the library table: I always said that there was no use in letting those books stay in cloth bindings: that reminds me, — I had better get my magazine sets bound before they cost too much: all the same, I don't like to spare those articles of Brown's; I shall want them for — ah! all this waste of time over that absurd traction engine! ' Every one will be able to parallel this series of ideas from his own experience. It is an illustration of the second form of the association of ideas, successive associa- tion.
The phrase, ' association of ideas,' is doubly misleading. In the first place, it is not ideas which '• associate,' but the elementary pro- cesses of which ideas are composed. And secondly, the connec- tion is not well described by the term 'association,' which implies a mere juxtaposition of things which remain, after they have been placed together, precisely what they were before.
The expression has come down to us from a psychology which did regard ideas and their connection in the way indicated: which took the idea of a pen or an inkstand to be something just as stable and clearly outlined as the pen or the inkstand itself, and looked upon the ' association ' of the two ideas as a mechanical attachment of one bit of mind, one independent experience, to another. Although this theory is not held to-day, the phrase has gained such wide acceptance that it can hardly be banished from our psychological vocabulary.
§ 53. Simultaneous Association. — Our first aim must be to get a clear understanding of the difference between the idea, or perception, and the simultaneous association of ideas. We shall do this most easily if we notice, first of all, the points in which the two processes are alike, and only after these are defined proceed to define that in which they differ.
(i) As regards the elementary processes contained in them, no hard and fast line of distinction can be drawn between the perception or idea and the simultaneous asso- ciation of ideas. Both prove, when analysed, to be com- plexes of sensations. From this point of view the idea of an arm-chair (§ 43), which contains both visual and tactual elements, might just as well be described as a simultaneous association of those elements; and the association of vis- ual picture and word in the instance of the traction engine, given in the preceding Section, might just as well be called a complete or perfect idea of the traction engine. If the two processes differ at all in composition, the difference is that the idea is simpler, contains fewer elementary pro- cesses, than the simultaneous association of ideas. But this rule has so many exceptions that we cannot safely follow it in distinguishing them.
(2) Nor do the idea and the simultaneous association of ideas differ as regards the way in which their component processes are connected, grouped together in consciousness. The elements of taste, smell, touch and sight which are contained in the idea of lemonade are * associated ' in that 192 The Association of Ideas idea, the elements of pressure and vision, or of pressure and audition (verbal local sign), which are contained in the tactual idea of locality, are ' associated ' in that idea, — just as, again, the visual picture and word are associated in our instance of simultaneous association. If the two processes differ at all in the connection of their elements, the differ- ence is that the elements in the idea are more closely and invariably associated than the elements of the simultaneous association. But this rule, again, has many exceptions. The elements of touch and vision in the idea of an arm- chair are not more closely connected with each other than with the verbal idea * arm-chair.' Yet touch and vision together give us an idea; the same elements phts the verbal idea, a simultaneous association of ideas.
(3) The difference between the two j^rocesses, then, lies neither in the part-processes which they contain, nor in the manner in which these components are grouped together. It must be sought elsewhere. Put briefly, it is this: that the elementary processes in the idea are pro- cesses which have never before been in connection with others, whereas the elementary processes in the simultane- ous association of ideas have already played a part in some idea. The idea is the concrete mental process which stands nearest to bare sensation: it is in the idea that the organism makes its first conscious adjustment to the natural world. The difference between the sensation which has not, and the sensation which has, taken part in this conscious adjustment is not a difference of quality or intensity, extent or duration. It is only that the one is raw material; the other the same material after it has been turned to account by the organism for some practical purpose. The one means nothing: it does not acquire a meaning until it has entered into an idea; for it is not the bare sensation, but the idea, which corresponds to an object or process in the physical world, and signifies this object or process to the organism. The other is significant: it brings a meaning with it, because it has, at some time or other, formed part of an idea or perception, i.e.^ of the conscious representative of a physical object or physical process. The sensation which has been associ- ated in the past, is ready to fall anew into associative con- nections; the sensation which has never been associated, has to find its place, so to speak, in the course of experi- ence. Or again: the sensation which enters into an idea is the sensation which we obtain by scientific analysis, the independent simple process of Chapter II; the sensation which enters into a simultaneous association of ideas is the sensation as we get it approximately in laboratory experience (§ 17; cf. § 74), a process which has a habit, a liability to connect with other sensations in the future, as it has connected before.
Two forms of simultaneous association are of especial interest. As they are at the same time typical of simul- taneous association in general, we may confine our discus- sion of the process to them.
(i) When once an idea has taken shape, — whether it be the idea of locality or of rhythm, of form or of melody, — it is henceforth at the disposal of consciousness as a whole, as a total process. There is no need of its con- scious re-formation. However slowly we may have learned the fact that objects lie in space at a distance from us, and however many mistakes we made before the idea of dis- tance was fully formed, we now have it as part of our mental furniture, ready for use upon all occasions. And o 194 'TJie Association of Ideas the same is true of all the kinds of idea discussed in the foregoing chapter.
It will often happen, then, that when an impression, a complex of stimuli, is presented to the organism, the appearance of the corresponding idea in consciousness arouses some one or other of these available ideas, which joins with the given idea and supplements it. The per- ception or idea, itself significant of some external object or process, is thus set in its proper place in our conscious plan or map of the physical world; it is arranged among our existing stock of perceptions or ideas, and brought into connection with them. In such cases we speak of the associative stipplementing of an idea. Associative sup- plementing is the first sub-form of simultaneous association.
Let us take, by way of illustration, our idea of the distance of an object from our own body. This idea was originally formed from sensation processes, whether sensations of strain from the muscles of the eyeball, or retinal sensations, or both together (§44). As bare sensations, these processes were meaningless; they acquired significance only when combined in the idea.
But when we are judging distance, in adult life, we are not con- cerned to notice the formative sensations of the original distance idea. An object is before us, and our perception of it as an object is at once associatively supplemented by the idea of its distance. Thus (i) if the object is small, we regard it (other things equal) as remote: the smaller a thing looks, the farther off must it be. The idea of size is here associatively supplemented by that of dis- tance. (2) If the distribution of lights and shades upon the surface of the object is of a certain kind, its perception is supple- mented, in just the same way, by an idea of distance. A theatre stage may be made to appear much deeper than it really is, if the lights and shades are skilfully distributed upon back-scene and side-pieces. (3) If the object is indistinct, its outlines blurred, the idea of remoteness comes up at once to supplement it. The less clear a thing is, the farther off is it, other things equal. (4) If there are a large number of objects intervening between our- selves and the object at which we are looking, the idea of re- moteness is again associated to it. (5) And if, as we pass rapidly through a landscape, e.g., as we sit in a railway carriage, an object flashes quickly by us, we know at once that it is near; if it glides by slowly, we know that it is distant. The perception is associ- atively supplemented, so that it makes way for a simultaneous association of ideas.
So close is the connection in these cases between the given idea and the idea which supplements it, that we are apt to lose sight of the way in which this supplementary idea was originally formed, and to look upon it as the direct consequence of the other. Really, of course, the supplementary idea must have previously taken shape, — or it could not now be associated to the given idea. We could not say: " See how clearly the trees stand out upon that hill! It can't be more than two or three miles off" unless we had the idea of distance at our disposal, before we noticed the clearness of the impressions. Clearness of outline is one of the original factors in the idea of form (§ 45); it is not a factor in the idea of distance. The exclamation involves an association of two ideas, of form and of distance.